The recent proliferation of Wi-Fi access points in wireless local area networks (WLANs) has made it possible for navigation systems to use these access points for position determination, especially in areas where there are a large concentration of active Wi-Fi access points (e.g., urban cores, shopping centers, office buildings, and so on). For example, a client device or station (STA) such as a cell phone or tablet computer may use the round trip time (RTT) of signals transmitted to and from the access points (APs) to determine the distances between the STA and the APs. Once the distances between the STA and three or more APs are determined, the location of the STA may be estimated using trilateration techniques.
More generally, the distance between a pair of devices may be determined using the RTT of signals exchanged between the devices during ranging operations. Because ranging operations are becoming more and more important (e.g., for indoor positioning), it is desirable to increase the accuracy of ranging operations using minimal capacity of the wireless medium.